Procedure for production of cabled coaxial pairs



Dec. 13, 1949 I v ,vos 2,491,235

PROCEDURE FOR PRODUCTION OF CABLEDCOAXIAL runs Filed Oct. 21, 1946 Fig.5

Patented Dec. 13, 1949 S PATENT OFFICE PROCEDURE FOR PRODUCTION OF CABLED COAXIAL PAIRS Mauritz Vos, Stockholm, Sweden, assignor to Telefonaktiebolaget L. M. Ericsson, Stockholm, Sweden, a company of Sweden Application October 21, 1946, Serial No. 704,566 In Sweden November 28, 1945 4 Claims. 1

The present invention relates to electrical cables, especially cables for the transmission of signal currents e, g. by carrier current telephony, and refers to a procedure for production of a cable or a part of a cable comprising cabled so called co-axial pairs. Such a co-axial pair forms a twin wire, in which one of the conductors, the inner conductor, lies in the center and the other, the outer conductor, surrounds the inner conductor as a tube. The inner conductor is centered in the outer conductor by means of spacers such as discs of insulating material. In addition, the interspace is usually filled with a suitable gas, e. g. air. The inner conductor can be made of a massive wire or a tube. The outer conductor is usually made of one or more bands of conducting material wound in spiral form around the spacers. The spiral is formed either when producing the co-axial pair itself or during the cabling of two or more col-axial pairs as shown in Figs. 5 and 6.

A composite cable comprising such a coaxial pair with an outer conductor made of one or more bands wound in spiral around the inner conductor has certain disadvantages for signal transmission. These disadvantages are due to the cutting, by the spirals of the outer conductor during flexing, of the lines of force surrounding the inner conductor, thus creating a disturbance in the electromagnetic field which interferes with the signal transmission. Attempts have been made to correct this by lessening the resistance between two consecutive turns in the spirals of the different bands, e. g. by giving the bands a suitable section. A certain decrease of the disturbing effect of the spiral can thus be obtained, but a great part of the disturbances still remains. The present invention relates to a method for the production of a composite cable of cabled co-axial pairs, which results in a flexibility in the co-axial pair which permits it to be coiled on a cable reel, and produces a flexibility in the compositecable which prevents the spiral twist of the outer conductor of the cabled pair from disturbing the signal transmission during flexing. When producing each co-axial pair, the metal band of the outer conductor is applied in spiral around the inner conductor with such a pitch and direction of the twist that the pitch of the spiral increases when two or more such pairs are cabled, the edges of the band, or bands, lying close to each other being allowed to glide along each other so that when the cabling is completed, the pitch of the spiral is infinite, i. e. the band, or bands, will lie parallel with the inner conductor without twist.

The invention can best be described by efer- 55 2 ence to the accompanying figures showing the method of. producing my cable in which,

Fig. 1 is a side view of a co-axial pair before stranding with other conductors,

Fig. 2 is a vertical cross-section of Fig. 1,

Fig. 3 is a side view of the same co-axial pair after being stranded together with other conductors,

Fig. 4 is a cross-section of Fig. 3,

Fig. 5 is a side view of a cable formed by stranding together two co-axial pairs with a segment broken away to show the relation of the inner and outer conductors, while Fig. 6 is a side view of a cable formed by stranding together four co-axial pairs with a segment broken away to show the relation of the outer and inner conductors.

Fig. 1 shows the stage in the production of a composite cable containing one or more co-axial pairs, wherein an inner conductor I has been provided with washers 3 of insulating material (e. g. polystyrol or a ceramic material), around which four bands or strips 2 have been wound in such a way, that they form a tube-shaped outer conductor. The strips are helically disposed with a relatively long lay when the pair is straightened, as shown in Fig. 1. When such a co-axial pair is cabled together with one or more other pairs or single wire lines, said pair will become spiralshaped, i. e. the axis of the pair will describe a spiral line. This arrangement does not affect the inner conductor. The outer conductor can be readily shaped if the contact surfaces in the joints between the bands 2 are able to glide with relation to each other. If this is possible, the spiralshape of the bands 2 will, on being cabled or stranded, be altered in relation to the inner conductor I. The pitch of the spiral will increase or decrease depending on the direction and pitch of both the original spiral of the bands before being cabled and of the spiral formed after cabling by the whole pair.

According to the invention, the bands 2 are wound with such a pitch and different pairs cabled together with such a pitch, that by said cabling, the spiral of the band 2 of the outer conductor is turned back to such an extent, that the pitch of the spiral will become infinite, i. e. the bands 2 will run parallel with the inner conductor and follow the spiral produced by different pairs being cabled together, as shown in Figs. 3, 4, 5 and 6. By the above procedure two objectives are simultaneously achieved; (1) the band of the outer conductor in the finished cable will not lie in spiral around the inner conductor so a l. h

3 that signal transmission is not interfered with and (2), the co-axial pair is flexible before being cabled and also after being cabled into the composite cable owing to the spiral shape of the whole co-axial pair.

I claim:

1. A method of manufacture of a flexible conductor for the transmission of high frequency electrical currents from one or more metallic strips forming a tubular structure, said strip or strips lying without twisting parallel to the axis of the tubular structure, consisting in arranging one or more metallic strips with :a relatively long lay in one helical direction in laterally interengaging relation to form a tubular structure, and stranding said conductor together with one or more conducting means in the opposite helical direction and with a lay so as to displace said strips longitudinally with respect to each eth r and ,position the strip p all l t h of said conductor.

2. A method of manufacture .of a flexible ,concluctor for the transmission of high frequency electrical currents ,from one or more metallic strips .Iormin ,a tubular structure, said strip or strips lying without twisting parallel "to the axis of the tubular structure, consisting in arranging one or more metallic strips with a relatively long lay one helical direction in laterally interengagi-ng relation to form .a tubular structure, winding ;-a metallic binding about said tubular structure with a pressure no greater than that permittin d s la ement of sa d t ips lon uritua ly with re pe to each other, and strand n condu to tgsct er wi one or more conductin means in the opposite helical direction and with-a iayso :as to displace said strips longiwithsresnect to each other and position the strips parallel to the axis ,of said conductor.

.8. A method of manufacture of a cable for transmission of high frequency electrical currents comprising a hollow conductor made up of one or more metallic strips forming a tubular structure, said strip or strips lying without twisting parallel to the axis of the tubular structure, consisting *in arranging tone or :mOre metallic strips with a relatively long lay "in one helical direction in laterally interengaging relation to form a tubular structure and stranding said conductor together with one or more conducting means in the opposite helical direction and with ;a ,lay ,so as to displace said strips longitudinally with respect to each other and position the strips parallel -to=the axis of said conductor.

a. A method of manufacture of a cable comprising ,a plurality of shielded conductor units each of said units comprising a tubular outer conductor made up oi one or more metallic strips, said strip or strips lying without twisting parallel to the axis of the tubular structure,

REFERENCES CI'IED The iollowing refierences :are of record in the 1 le .of this patent-1 UNITED STATES PATENTS :Name Date Windeler hummus, Dec. a 54939 Number 

